Wellbore servicing compositions and methods of making and using same

ABSTRACT

A method of servicing a wellbore in a subterranean formation comprising preparing a wellbore servicing fluid comprising cement, an aqueous fluid, and a cyclodextrin, a cyclodextrin derivative, or combination thereof; placing the wellbore servicing fluid in the wellbore and allowing the fluid to set. A wellbore servicing fluid comprising cement, aqueous fluid, and a cyclodextrin, cyclodextrin derivative, or combination thereof.

FIELD

This disclosure relates to servicing a wellbore. More specifically, itrelates to servicing a wellbore with cement compositions comprisingretarders and methods of making and using same.

BACKGROUND

Natural resources such as gas, oil, and water residing in a subterraneanformation or zone are usually recovered by drilling a wellbore down tothe subterranean formation while circulating a drilling fluid in thewellbore. After terminating the circulation of the drilling fluid, astring of pipe (e.g., casing) is run in the wellbore. The drilling fluidis then usually circulated downward through the interior of the pipe andupward through the annulus, which is located between the exterior of thepipe and the walls of the wellbore. Next, primary cementing is typicallyperformed whereby a cement slurry is placed in the annulus and permittedto set into a hard mass (i.e., sheath) to thereby attach the string ofpipe to the walls of the wellbore and seal the annulus. Subsequentsecondary cementing operations may also be performed.

Cementitious slurries can set very rapidly, e.g., within a few minutesat elevated temperatures with the rate of reaction increasing as thetemperature increases. As such, the thickening times of the compositionsmay be unacceptably short to allow them to be pumped to their desireddownhole locations, making the use of such compositions in wellcementing a challenge. For example, the drill pipe or the tool used tolower the piping in the wellbore may be cemented in place, causing delayin the completion of the wellbore. One method commonly employed tolengthen the thickening time of cementitious compositions is tointroduce set retarders into the compositions, thereby delaying the timeto setting of the cement. However, the effectiveness of many setretarders decreases with increasing temperature requiring the use ofmultiple retarders at varying concentrations. Thus, an ongoing needexists for set retarder compositions that function at elevatedtemperatures.

SUMMARY

Disclosed herein is a method of servicing a wellbore in a subterraneanformation comprising preparing a wellbore servicing fluid comprisingcement, an aqueous fluid, and a cyclodextrin, a cyclodextrin derivative,or combination thereof; placing the wellbore servicing fluid in thewellbore and allowing the fluid to set.

Also disclosed herein is a wellbore servicing fluid comprising cement,aqueous fluid, and a cyclodextrin, cyclodextrin derivative, orcombination thereof.

The foregoing has outlined rather broadly the features and technicaladvantages of the present disclosure in order that the detaileddescription that follows may be better understood. Additional featuresand advantages of the invention will be described hereinafter that formthe subject of the claims of the disclosure. It should be appreciated bythose skilled in the art that the conception and the specificembodiments disclosed may be readily utilized as a basis for modifyingor designing other structures for carrying out the same purposes of thepresent disclosure. It should also be realized by those skilled in theart that such equivalent constructions do not depart from the spirit andscope of the disclosure as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a depiction of γ-cyclodextrin.

FIGS. 2 and 3 are thickening time plots for the samples from example 1.

FIGS. 4 and 5 are plots of the compressive strengths for the samplesfrom example 1.

FIG. 6 is a plot of the thickening time as a function of retarderconcentration.

DETAILED DESCRIPTION

Disclosed herein are wellbore servicing fluids (WSF) and methods ofmaking and using same. In an embodiment, the WSF comprises acementitious material and a cyclodextrin. The cyclodextrin may functionto extend the thickening time of the cementitious composition whereinthe thickening time refers to the time required for the composition toachieve 70 Bearden units of Consistency (Bc). Consistency is a measureof the pumpability of a cement slurry measured in Bearden units (Bc),and when a cement slurry reaches a Consistency of 70 Bc, it is no longerconsidered a pumpable slurry.

In an embodiment, the WSF comprises a cyclodextrin, an inclusion complexthereof, or a derivative thereof. Generally, cyclodextrin is thought tobe a cyclic oligosaccharide comprising at least 6 glucopyranose unitsjoined by α-(1,4) glycosidic linkages. While cyclodextrins may have upto 150 or more glucopyranose units, the more common cyclodextrinscomprise 6, 7, or 8 (α, β, and γ, respectively) glucopyranose unitsjoined by α-(1,4) glycosidic linkages. Cyclodextrins comprising 6-8glucopyranose units can be represented as toroids as depicted in FIG. 1.Referring to FIG. 1, γ-cyclodextrin is represented as toroid 10 with alarger opening 12 and a smaller opening 14 of toroid 10 representing thesecondary and primary hydroxyl groups, respectively. In general, theexterior 16 of toroid 10 may be sufficiently hydrophilic for thecyclodextrin to possess some water solubility. Internal cavity 18 oftoroid 10 is generally apolar or relatively more hydrophobic and lesshydrophilic than the exterior of the molecule and, thus, may beattractive to hydrophobic or lipophilic molecules. For example, theinternal cavity (such as internal cavity 18) of the cyclodextrin or acyclodextrin derivative may be capable of hosting a hydrophobic portionof a “guest” compound to form an inclusion complex therewith. As usedherein, the term “inclusion complex” generally refers to the complexformed with the cyclodextrin functioning as a “host” to a “guest”compound that is contained or bound, wholly or partially, within theinternal cavity of the cyclodextrin.

In some embodiments, the WSF comprises a cyclodextrin derivative. Anysuitable methodology may be used in the preparation of a cyclodextrinderivative. For example, cyclodextrin derivatives may be prepared byintroducing different functional groups into the cyclodextrin moleculeby reaction with the primary hydroxyl and/or secondary hydroxyl groups.Because each type of hydroxyl group present in the cyclodextrin moietymay display a different reactivity, derivatizing cyclodextrins mayresult in an amorphous mixture that includes numerous isomers ofdifferent substituted cyclodextrin derivatives, for example when all theavailable hydroxyl groups are not completely derivatized. It iscontemplated that compositions comprising a mixture of cyclodextrinderivatives are suitable for use in the present disclosure.

In an embodiment, derivatization of the cyclodextrin is carried outunder conditions that result in some portion of the cyclodextrinremaining underivatized. For example, the reaction may be carried out toresult in partial derivatization of the cyclodextrin such that someportion of the free hydroxyl groups in a cyclodextrin molecule remainsunderivatized. In an embodiment, the average degree of derivatization isless than about 3 per glucopyranose ring. In an embodiment, acyclodextrin derivative contains at least one underivatized hydroxylgroup per toroid ring.

Examples of cyclodextrin derivatives suitable for use in the presentdisclosure include, but are not limited to: (1) acylated cyclodextrincontaining acetyl, propionyl, butyryl, or other suitable acyl groups;(2) hydroxyalkylated cyclodextrin containing hydroxyethyl,hydroxypropyl, or other suitable hydroxy-alkyl groups; (3) carboxylatedcyclodextrin containing carboxymethyl, carboxyethyl, or other suitablecarboxyalkyl groups, and (4) alkylated cyclodextrin containing methyl,ethyl, propyl, benzyl, or other suitable alkyl groups. In an embodiment,the cyclodextrin derivative comprises a glucosyl or maltosyl moiety suchas glucosyl cyclodextrins and maltosyl cyclodextrins. Non-limitingexamples of cyclodextrin derivatives suitable for use in the presentdisclosure include methyl cyclodextrins, hydroxyethyl cyclodextrins,hydroxypropyl cyclodextrins, 2-hydroxyethyl cyclodextrins, carboxymethylcyclodextrins, carboxyethyl cyclodextrins, glucosyl-α-cyclodextrin,maltosyl-α-cyclodextrin, glucosyl-β-cyclodextrin,maltosyl-β-cyclodextrins, methyl-β-cyclodextrin,2-hydroxypropyl-β-cyclodextrin, hydroxyethyl-β-cyclodextrin,2-hydroxypropyl-γ-cyclodextrin, or combinations thereof.

In an embodiment, the WSF comprises a cyclodextrin derivative comprisingan oligomerized or polymerized cyclodextrin such as cyclodextrin dimersand cyclodextrin trimers. Cyclodextrin dimers generally include twocyclodextrin molecules covalently coupled or crosslinked together.Cyclodextrin trimers generally include three cyclodextrin moleculescovalently coupled or crosslinked together. Polymerized cyclodextrinsgenerally include a unit of 10 or more cyclodextrin molecules covalentlycoupled or crosslinked together. Non-limiting examples of oligomerizedand/or polymerized cyclodextrins suitable for use in the presentdisclosure include those containing carboxymethyl cyclodextrins,glucosyl cyclodextrins, maltosyl cyclodextrins, hydroxypropylcyclodextrins, and 2-hydroxypropyl cyclodextrins. Cyclodextrins andcyclodextrin derivatives are widely commercially available and may beobtained from companies such as CTD, Inc., High Springs, Fla.

Hereinafter, the disclosure will refer to the use of cyclodextrins inthe WSF although cyclodextrin derivatives of the type disclosed hereinare also contemplated for use in the fluid. In an embodiment,cyclodextrin is present in the WSF in an amount of from about 0.1 wt. %to about 5.0 wt. % based on the weight of cement (bwoc), alternativelyfrom about 0.1 wt. % to about 4 wt. % or alternatively from about 0.1wt. % to about 3.0 wt. %. In an embodiment, cyclodextrin functions toretard the setting of the WSF over the disclosed concentrations.

In an embodiment, the WSF comprises a cementitious material such as ahydraulic cement that sets and hardens by reaction with water. Examplesof hydraulic cements include but are not limited to Portland cements(e.g., classes A, B, C, G, and H Portland cements), pozzolana cements,gypsum cements, phosphate cements, high alumina content cements, silicacements, high alkalinity cements, shale cements, acid/base cements,magnesia cements such as Sorel cements, fly ash cement, zeolite cementsystems, cement kiln dust cement systems, slag cements, micro-finecement, metakaolin, and combinations thereof. Examples of such materialsare disclosed in U.S. Pat. Nos. 6,457,524; 7,077,203; and 7,174,962,each of which is incorporated herein by reference in its entirety. TheWSF may comprise cementitious material in an amount of from about 10 wt.% to about 85 wt. %, alternatively from about 40 wt. % to about 75 wt.%, alternatively from about 50 wt. % to about 70 wt. % by weight of theWSF.

The WSF may include a sufficient amount of an aqueous fluid (e.g.,water) to form a pumpable cementitious slurry. The water may be freshwater or salt water, e.g., an unsaturated aqueous salt solution or asaturated aqueous salt solution such as brine or seawater. The water maybe present in the amount from about 20 to about 180 percent by weight ofcement, alternatively from about 28 to about 60 percent by weight ofcement, alternatively from about 36 to about 66 percent by weight ofcement. The cementitious slurry may have a density of from about 7pounds per gallon (ppg) to about 20 ppg, alternatively from about 10 ppgto about 18 ppg, or alternatively from about 13 ppg to about 17 ppg.

In an embodiment, the WSF may further comprise one or more additives ormodifying agents as deemed necessary to impart desired physicalproperties. Such additives may include but are in no way limited toresins, latex, stabilizers, silica, microspheres, aqueoussuperabsorbers, viscosifying agents, suspending agents, dispersingagents, salts, accelerants, surfactants, retardants, defoamers,settling-prevention agents, weighting materials, fluid loss controlagents, elastomers, vitrified shale, gas migration control additives,formation conditioning agents, or other additives or modifying agents,and/or combinations thereof. Effective amounts of these additives may beincluded singularly or in combination using any suitable methodology.

In an embodiment, a WSF of the type described herein comprisescementitious material, water, and a cyclodextrin all of the type and allpresent in amounts previously described herein. Alternatively, a WSF ofthe type described herein comprises cementitious material, water, and aβ-cyclodextrin. A WSF containing cementitious material, water, and acyclodextrin is hereinafter designated WSF-X.

The components of the WSF-X may be combined in any order desired by theuser to form a slurry that may then be placed into a wellbore andallowed to set. The components of the WSF-X may be combined using anymixing device compatible with the composition, for example a bulk mixeror a recirculating mixer. In some embodiments, the WSF-X is formed bypremixing the cyclodextrin with the cementitious material prior to theaddition of other components of the WSF-X. For example, a method ofpreparing the WSF-X may comprise dry blending a cementitious materialwith a cyclodextrin both of the type described previously herein. In anembodiment, the cementititous material and cyclodextrin are contactedwith any other dry components of the WSF-X prior to the introduction ofa liquid component. Alternatively, cyclodextrin can be added to mixwater prior to the addition of solid cement blend.

In an embodiment, the thickening time of the WSF-X varies linearly as afunction of the cyclodextrin concentration such that the WSF-X displayschanges in thickening time that are on approximately the same order ofmagnitude of the cyclodextrin concentration changes. For example, at aspecified temperature within the herein disclosed ranges, doubling theconcentration of cyclodextrin in the WSF-X may approximately double thethickening time of the WSF-X. Alternatively, tripling the concentrationof cyclodextrin in the WSF-X may approximately triple the thickeningtime of the WSF-X. In an embodiment, at higher temperature, doubling ortripling the cyclodextrin concentration may increase the thickening timeby from about four to about twelve times the original value. Herein,higher temperatures refer to a temperature range of from about 180° F.to about 500° F., alternatively from about 200° F. to about 450° F., oralternatively from about 250° F. to about 400° F.

The ratio of change in thickening time (in hours) to change incyclodextrin concentration (% by weight of cement) may be obtainedgraphically by the slope of the graph in which thickening time isplotted as a function of cyclodextrin concentration. In an embodiment,the thickening time, in hours, of the WSF-X displays a responsiveness at250° F. to the concentration of cyclodextrin (% by weight of cement)that is equal to or less than about a factor of 10, alternatively equalto or less than about a factor of 8, or alternatively equal to or lessthan about a factor of 3. In an alternative embodiment, the WSF-Xdisplays a thickening time that varies by equal to or less than about1000% with a change in cyclodextrin concentration of about 100%,alternatively equal to or less than about 800%, or alternatively equalto or less than about 300%.

In an embodiment, the cyclodextrin may display an operationaltemperature of greater than about 250 degrees, alternatively greaterthan about 300 degrees, or alternatively greater than about 375 degreesFahrenheit. Herein, the operational temperature refers to thetemperature range over which the cyclodextrin may function as a setretarder with a predictable thickening time response for a specifiedchange in temperature at a fixed cyclodextrin concentration. Thethickening time response to cyclodextrin concentration at a specifiedtemperature (i.e., the ratio of change in thickening time (in hours) asa function of change in temperature at a specified cyclodextrinconcentration) may be obtained graphically by the slope of the graph inwhich thickening time is plotted as a function of temperature or changein temperature. In an embodiment, the thickening time, in minutes, ofthe WSF-X displays a responsiveness to the temperatures (in Fahrenheit),within the operational window, at a concentration of 2.2% cyclodextrinby weight of cement that is equal to or less than about a factor of 10minutes per degree increase in temperature, alternatively equal to orless than about a factor of 8 minutes per degree increase intemperature, or alternatively equal to or less than about a factor of 3minutes per degree increase in temperature.

The WSF-X may exclude conventional set retarders as are known in theart. In such embodiments, the cyclodextrin may function as a primary setretarder which results in the WSF-X having a thickening time of fromabout 3 hours to about 20 hours, alternatively from about 3 hours toabout 15 hours, or alternatively from about 3 hours to about 12 hours ata temperature in the range of equal to or less than about 400° F.;alternatively equal to or less than about 300° F.; alternatively equalto or less than about 250° F., or alternatively from about 200° F. toabout 400° F. In an embodiment, the cyclodextrin acts as the sole setretarder in the WSF-X at temperatures equal to or less than about 400°F. As will be understood by one of ordinary skill in the art, at highertemperatures (e.g., greater than about 300° F.) conventional setretarders may display a reduced effectiveness in prolonging thethickening times of the cement slurries. Consequently, conventionalcement slurries may contain more than one type of set retarder with theset retarders having different operational windows. Compositions of thetype disclosed herein (i.e., WSF-X) which employ cyclodextrins as theset retarder may display a broad operational window thereby avoiding theuse of multiple set retarders. For example, cyclodextrin may function toretard a WSF-X in a temperature range of from about 80° F. to about 400°F., alternatively from about 80° F. to about 350° F., alternatively fromabout 200° F. to about 400° F., or alternatively from about 100° F. toabout 300° F. The operational window is typically associated with theparticular wellbore servicing operation being carried out. For example,the temperature of the well in addition to the depth of the well willinfluence the length of time it will take to pump and safely place theslurry in the zone of interest. For example, the length of time it willtake to pump and safely place the slurry in the zone of interest may bein the range of from about 2 to about 8 hrs or from about 4 to about 10hrs. In an embodiment, the cyclodextrin allows the slurry to remainpumpable at the bottom hole circulating temperature of the well and thedepth of the well to which the slurry needs to be pumped.

In an embodiment, the WSF-X may comprise one or more additionalretarders, such as for example tartaric acid or sodium pentaborate. Itis contemplated such compositions may be designed by one of ordinaryskill in the art with the benefits of this disclosure to meet one ormore user and/or process desired needs.

In an embodiment, the WSF-Xs may be employed in well completionoperations such as primary and secondary cementing operations. The WSF-Xmay be placed into an annulus of the wellbore and allowed to set suchthat it isolates the subterranean formation from a different portion ofthe wellbore. The WSF-X thus forms a barrier that prevents fluids in thesubterranean formation from migrating into other subterraneanformations. Within the annulus, the WSF-X also serves to support aconduit, e.g., casing, in the wellbore. In an embodiment, the wellborein which the WSF-X is positioned belongs to a multilateral wellboreconfiguration. It is to be understood that a multilateral wellboreconfiguration refers to a primary wellbore with one or more secondarywellbore branches radiating from the primary borehole.

In secondary cementing, often referred to as squeeze cementing, thesealant composition may be strategically positioned in the wellbore toplug a void or crack in the conduit, to plug a void or crack in thehardened sealant (e.g., cement sheath) residing in the annulus, to pluga relatively small opening known as a microannulus between the hardenedsealant and the conduit, and so forth. Various procedures that may befollowed to use a sealant composition in a wellbore are described inU.S. Pat. Nos. 5,346,012 and 5,588,488, which are incorporated byreference herein in their entirety.

The WSF-X may be introduced to the wellbore to prevent the loss ofaqueous or non-aqueous drilling fluids into loss-circulation zones suchas voids, vugular zones, and natural or induced fractures whiledrilling. In an embodiment, the WSF-X is placed into a wellbore as asingle stream and activated by downhole conditions to form a barrierthat substantially seals loss circulation zones. In such an embodiment,the WSF-X may be placed downhole through the drill bit forming acomposition that substantially eliminates the lost circulation. Methodsfor introducing compositions into a wellbore to seal subterranean zonesare described in U.S. Pat. Nos. 5,913,364; 6,167,967; and 6,258,757,each of which is incorporated by reference herein in its entirety.

The WSF-X, after hardening, may form a non-flowing, intact mass withgood strength and capable of withstanding the hydrostatic pressureinside the loss-circulation zone. Said WSF-X may plug the zone andinhibit the loss of subsequently pumped drilling fluid thus allowing forfurther drilling.

In an embodiment, the cyclodextrin included in the WSF-X may function asa dispersant which displays an improved dispersing ability when comparedto an otherwise similar wellbore servicing fluid lacking cyclodextrin.In an embodiment, the dispersing ability of the cyclodextrin results ina reduction in viscosity of the WSF of equal to or greater than about15%, alternatively equal to or greater than about 30%, or alternativelyequal to or greater than about 40% when compared to an otherwise similarwellbore servicing fluid lacking cyclodextrin at a specified shear rate.Herein, the dispersing ability is measured by obtaining FANN viscosmeterreadings at room temperature or higher for speeds of 3, 6, 30, 60, 100,200, 300, and 600 rpm.

In an embodiment, the WSF-X displays right angle set. Herein, rightangle set refers to the near right angle increase in viscosity (orconsistency) shown in a plot of viscosity (or consistency) over time forthe WSF-X. Specifically, it refers to the ability of the slurry toexhibit a relatively constant viscosity for a period of time after theyare initially prepared and while they are being placed in their intendedlocations in the wellbore, i.e., during the period when the slurry is inmotion. Eventually, the cement compositions (i.e., WSF-X) quickly setsuch that the viscosity (or consistency) increases from about 35 Bc toequal to or higher than 70 Bc in equal to or less than about 60 minutes,alternatively equal to or less than about 50 minutes, alternativelyequal to or less than about 40 minutes, alternatively equal to or lessthan about 30 minutes, alternatively equal to or less than about 20minutes, alternatively equal to or less than about 10 minutes,alternatively equal to or less than about 1 minute. This sudden jump inviscosity may be very desirable in preventing unwanted events such asgas or water migration into the slurry because it indicates the quickformation of impermeable mass from a gelled state after placement.

EXAMPLE

The following examples are given as particular embodiments of thedisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the examples are given by way of illustration and arenot intended to limit the specification or the claims in any manner.

Example 1

The effects of including a cyclodextrin of the type described herein ona cement slurry were investigated. Specifically, a 15.8 pound per gallon(ppg) cement slurry containing β-cyclodextrin, 56 wt. % water, 100 wt. %class G cement, 35 wt. % SSA-2 and 0.5 wt. % HALAD-344 was prepared bydry blending β-cyclodextrin, SSA-2, and HALAD-344 and then mixing withwater. The weight percentages given are by weight of cement. SSA-2coarse silica flour is a sand weight additive and HALAD-344 fluid lossadditive is a fluid loss control material both of which are commerciallyavailable from Halliburton Energy Services, Inc. The thickening times ofthe slurry as a function of temperature and the concentration ofβ-cyclodextrin was determined. These results are presented in Table 1.

TABLE 1 Thickening Time Temperature (° F.) β-cyclodextrin (wt. %)(Hour:min.) 220 0.4 7:53 250 0.7 4:14 1.1 7:32 1.3 10:30  300 1.6 9:36350 1.8 8:19 2.2 11:52  375 2.2 5:31 400 2.2 3:16 2.4 3:48

The results demonstrate that β-cyclodextrin functions as an effectiveset retarder over a wide temperature range (e.g., from 220° F. to 400°F.) and that the thickening time can be varied by varying theconcentration of β-cyclodextrin. Thickening time plots of the slurrycontaining 0.7 wt. % β-cyclodextrin at 250° F. and the slurry containing2.2 wt. % β-cyclodextrin at 350° F. are presented in FIGS. 2 and 3respectively. The observed relatively long thickening time of 7 hrs and53 min at 220° F. even at a low β-cyclodextrin concentration of 0.4%bwoc indicates that at low temperatures, for example in the range of 80°F. to 180° F., the concentrations of the retarder required to observe areasonable thickening times will be very low (for example, less than0.1%) to allow for accurate weight measurements. In such situations, theretarder can be diluted with inert materials such as silica or gypsum inany ratio that allows for increased bulk of the material for accurateweight measurements.

The compressive strength of samples set at 250° F. was investigatedusing an Ultrasonic Cement Analyzer (UCA). Herein, the compressivestrength is defined as the capacity of a material to withstandaxially-directed pushing forces. The samples were of a 16.8 ppg cementslurry containing the indicated set retarder, 56 wt. % water, 100 wt. %class G cement, 35 wt. % SSA-2 and 0.5 wt. % HALAD-344 were prepared bydry blending the set retaarder, SSA-2, and HALAD-344 and then mixingwith water. Slurry 1 contained 0.7 wt. % (bwoc) β-cyclodextrin, Slurry 2contained 1.1 wt. % (bwoc) β-cyclodextrin and Slurry 3 contained 1.1 wt.% (bwoc) SCR-100. SCR-100 is a non-lignosulfate cement retardercommercially available from Halliburton Energy Services, Inc. Theresults are summarized in Table 2.

TABLE 2 24 hour Slurry Thickening time Time Time compressive No.(Hours:min) @50 psi @500 psi strength (psi) 1 2:38 3:49 4:16 4536 2 4:265:50 6:17 4776 3 3:06 3:44 4:18 3397

The results demonstrate that inclusion of β-cyclodextrin in the cementslurry did not prevent the development of compressive strength. The timelag observed between the thickening time and the development of 50 psiof compressive strength is advantageously narrow. The cement sampleshaving β-cyclodextrin as the retarder after 24 hours displayed anultimate compressive strength of greater than 4500 psi (Slurries 1 and2) while the slurry having SCR-100 as a set retarder displayed anultimate compressive strength of about 3400 psi (Slurry 3).Representative UCA charts of 16.8 ppg cement slurries set at 250° F.having 0.7 wt. % or 1.1 wt. % β-cyclodextrin are shown in FIGS. 4 and 5respectively. These figures demonstrate that 50% of the ultimatecompressive strength is developed in less than 2 hours from the time theslurry begins to develop gel strength.

Example 2

The ability of cyclodextrins of the type disclosed herein to act asdispersants was investigated by studying the slurry rheology at 140° F.Two slurries of 16.5 ppg density using Class G cement were prepared.Slurry 4 was a comparative cement slurry which contained noβ-cyclodextrin. Slurry 5 contained 0.5 wt. % (bwoc) of β-cyclodextrin.The slurries were conditioned at 140° F. for 20 minutes and then therheological property was measured using a FANN 35 viscometer at 3, 6,30, 60, 100, 200, 300 and 600 RPM and the results are summarized inTable 3.

TABLE 3 Fann Readings Slurry No. 600 300 200 100 60 30 6 3 4 154 141 122100 84 53 16 10 5 82 46 35 24 21 16 10 6

The results demonstrate that slurries containing β-cyclodextrindisplayed a dispersing ability.

Example 3

The thickening time of the cement slurry as a function of retarderconcentration was investigated. Specifically, a base slurry was preparedas described in Example 1. To the base slurry was added the indicatedamount of either β-cyclodextrin or HR-800 cement retarder and thethickening time determined. HR-800 cement retarder is a non-lignin,acyclic oligosaccharide type cement retarder commercially available fromHalliburton Energy Services, Inc. HR-800 was added as a material dilutedwith gypsum in a 2:1 ratio. The results are plotted in FIG. 6. Theresults demonstrate that when the retarder concentration is changed by0.1% bwoc, the thickening time for HR-800 changes by 2.6 hours whereassamples containing β-cyclodextrin displayed a change in thickening timeof about 1.0 hour (slope=10 or factor of 10:1) with the same change inretarder concentration. These results indicate that β-cyclodextrindisplays a set retarding ability that is not overly sensitive toconcentration which may be advantageously employed in the design ofrobust cement slurry formulations which provide suitable thickeningtimes even when slight inadvertent changes to the additive concentrationoccur in the field.

While embodiments of the disclosure have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the disclosure. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the disclosuredisclosed herein are possible and are within the scope of thedisclosure. Whenever a numerical range with a lower limit and an upperlimit is disclosed, any number and any included range falling within therange are specifically disclosed. In particular, every range of values(of the form, “about a to about b,” or, equivalently, “fromapproximately a to b,” or, equivalently, “from approximately α-b”)disclosed herein is to be understood to set forth every number and rangeencompassed within the broader range of values. Use of the term“optionally” with respect to any element of a claim is intended to meanthat the subject element is required, or alternatively, is not required.Both alternatives are intended to be within the scope of the claim. Useof broader terms such as comprises, includes, having, etc. . . . ,should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,etc. Also, the terms in the claims have their plain, ordinary meaningunless otherwise explicitly and clearly defined by the patentee.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present disclosure. Thus, the claims are a further description andare an addition to the embodiments of the present disclosure. Thediscussion of a reference herein is not an admission that it is priorart to the present disclosure, especially any reference that may have apublication date after the priority date of this application. Thedisclosures of all patents, patent applications, and publications citedherein are hereby incorporated by reference, to the extent that theyprovide exemplary, procedural, or other details supplementary to thoseset forth herein.

What is claimed is:
 1. A method of servicing a wellbore in asubterranean formation comprising: preparing a wellbore servicing fluidcomprising a cementitious material, an aqueous fluid, and at least oneof a cyclodextrin, a cyclodextrin derivative, and any combinationthereof; placing the wellbore servicing fluid in the wellbore; andallowing the wellbore servicing fluid to set.
 2. The method of claim 1wherein the cyclodextrin is selected from the group consisting of:α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and any combinationthereof.
 3. The method of claim 1 wherein the cyclodextrin derivate isselected from the group consisting of: acylated cyclodextrin,hydroxyalkylated cyclodextrin, carboxylated cyclodextrin, alkylatedcyclodextrin, and any combination thereof.
 4. The method of claim 1wherein the cyclodextrin derivatives is selected from the groupconsisting of: a glucosyl cyclodextrin, a maltosyl cyclodextrin, amethyl cyclodextrin, a hydroxyethyl cyclodextrin, a hydroxypropylcyclodextrin, a 2-hydroxyethyl cyclodextrin, a carboxymethylcyclodextrin, a carboxyethyl cyclodextrin, a glucosyl-α-cyclodextrin, amaltosyl-α-cyclodextrin, a glucosyl-β-cyclodextrin, amaltosyl-β-cyclodextrin, a methyl-β-cyclodextrin, a2-hydroxypropyl-β-cyclodextrin, a hydroxyethyl-β-cyclodextrin, a2-hydroxypropyl-γ-cyclodextrin, and any combination thereof.
 5. Themethod of claim 1 wherein the wherein the cyclodextrin derivatives isselected from the group consisting of: a cyclodextrin dimer, acyclodextrin trimer, a polymerized cyclodextrin, and any combinationthereof.
 6. The method of claim 1 wherein the cyclodextrin comprisesβ-cyclodextrin.
 7. The method of claim 1 wherein the cyclodextrin,cyclodextrin derivative, or combination thereof is present in thewellbore servicing fluid in an amount of from about 0.1 wt. % to about5.0 wt. % by weight of cement.
 8. The method of claim 1 where in thecementitious material comprises at least one cement selected from thegroup consisting of: a Portland cement, a pozzolana cement, a gypsumcement, a phosphate cement, a high alumina content cement, a silicacement, a high alkalinity cement, a shale cement, an acid/base cement, amagnesia cement, a fly ash cement, a zeolite cement system, a cementkiln dust cement system, a slag cement, a micro-fine cement, ametakaolin, and any combination thereof.
 9. The method of claim 1wherein the cementitious material is present in the wellbore servicingfluid in an amount of from about 10 wt. % to about 85 wt. % by weight ofwellbore servicing fluid.
 10. The method of claim 1 wherein the aqueousfluid is present in the wellbore servicing fluid in an amount of fromabout 20 wt. % to about 180 wt. % by weight of cement.
 11. The method ofclaim 1 wherein the wellbore servicing fluid displays a thickening timeof from about 3 to about 20 hours at a temperature of less than or equalto about 400° F.
 12. The method of claim 1 wherein the wellboreservicing fluid displays a right angle set.
 13. The method of claim 1wherein the thickening time of the wellbore servicing fluid varieslinearly as a function of cyclodextrin concentration.
 14. The method ofclaim 1 wherein the wellbore servicing fluid displays an operationalwindow of at least from about 80° F. to about 400° F.
 15. The method ofclaim 1 wherein the wellbore servicing fluid displays a change inthickening time at 250° F. of equal to or less than about a factor of 10in response to a change in concentration of at least one of thecyclodextrin, the cyclodextrin derivative, and any combination thereof.